In general, in a manufacturing step of a semiconductor device, a fine pattern is formed using a photolithography method. Further, in forming the fine pattern, a large number of transfer masks (also generally called photomasks) are generally used. In a transfer mask, in general, a light shielding blocking fine pattern formed of a metal thin film or the like is provided on a transparent glass substrate. The photolithography method is also used in manufacturing this transfer mask.
The transfer mask is an original plate for transferring the same fine pattern in high volume. Therefore, the dimensional accuracy of a pattern formed on the transfer mask directly affects the dimensional accuracy of the fine pattern to be manufactured. As the degree of integration of a semiconductor circuit is improved, the dimensions of the pattern become smaller, and the accuracy of the transfer mask is required to be higher.
Hitherto, as such transfer mask, there have been well known a binary mask, in which a transfer pattern formed of a light shielding film is formed on a transparent substrate, e.g., a glass substrate, a phase shift mask, in which a transfer pattern formed of a phase shift film, or of a phase shift film and a light shielding film is formed on the transparent substrate, and other type of masks. There has also been known a halftone-type phase shift mask, in which a light shielding band is formed in a peripheral portion of a transfer pattern forming region.
For example, in WO-A-2004/090635 (Patent Document 1), there is described, as a mask blank for manufacturing a halftone-type transfer mask, a mask blank having the thin-film structure including, from a substrate side, a metal silicide-based transfer mask film (light-semitransmissive film), a light shielding film made of a chromium-based compound, and a hard mask film made of a silicon compound.